The optimal treatment of the proliferative forms of kidney disease associated with systemic lupus erythematosus is controversial. The efficacy of intensive, intermittent immunosuppressive drug therapy is being evaluated in patients with active lupus glomerulonephritis. A comparison is being made between intermittent pulse doses of corticosteroid and cyclophosphamide, as well as between a short and long course of pulse cyclophosphamide. Patients with renal biopsy documented active glomerulonephritis were treated with prednisone and randomized to receive concomitantly (a) intravenous pulse methylprednisolone monthly for 6 months, or (b) intravenous pulse cyclophosphamide monthly for 6 months, or (c) pulse cyclophosphamide monthly for 6 months followed by a maintenance regimen of pulse cyclophosphamide every 3 months for an additional two years. Results to date indicate a statistically significant, higher probability of progressive renal insufficiency in patients treated with pulse methylprednisolone than in patients treated with pulse cyclophosphamide.